Apparatus for charging compressed gas material breaking cartridges



March 3, 1942, F. H. ARMSTRONG APPARATUS FOR CHARGING GOMPRESSD GASMATERIAL BREAKING CARTRIDGES Filed May 9, 1941 3 Sheets-Sheet 1 March 3,1942. F, H, ARMSTRONG 2,274,771

APPARATUS FOR CHARGING COMPRESSED GAS MATERIAL BREAKING CARTRIDGES FiledMay 9, 1941 5 Sheets-Sheet 2.

March 3, 1942. F. H. ARMsTRoNG 2,274,771

APPARATUS FOR CHARGING COMPRESSED GAS MATERIAL BREAKING CARTRIDGES FiledMay 9, 1941 3 Sheets-Sheet 3 Uyuivi UNITED STATES PATENT OFFICEAPPARATUS FOR CHARGING COMPRESSED GAS MATERIAL BREAKING CARTRIDGES FrankH. Armstrong, Chicago, Ill., assignor to Cardox Corporation, Chicago,Ill., a corporation of Illinois Application May 9, 1941, Serial No.392,815

11 Claims.

This invention relates to new and useful improvements in apparatus forcharging reusable cartridges with compressed gases for use in breakingdown coal, or similar materials, in mines.

The possibility of employing highly compressed gases, such as air, as amedium for breaking down coal, or the like, in mines definitely wasestablished quite some time ago as a resultl of perfection of suchequipment items as:

1. A compressor unit which would develop the high pressures required tobreak down the coal; which could be operated at a satisfactorily lowmaintenance cost, and which would have a sufliciently long working lifeto permit its initial cost to be written oi at an economical rate.

2. A compressed gas receiver of proper strength and capacity to receivea suiicient volume of gas compressed to a proper value to permitcartridges to be charged therefrom in relatively rapid successionwithout causing the receiver pressure to drop below the desired maximumoperating pressure of the cartridges.

3. A cartridge of practical dimensions which would withstand the roughusage to which it was subjected under normal working conditions and therepeated recharging with the highly compressed gases.

4. A diierential pressure operated valve mechanism for releasing thecartridge charges which was capable of being operated a large number oftimes without having to be serviced, and which could be controlled at a.remote point with respect to the working face of the coal vein beingbroken down.

Even with the above items satisfactorily developed, coal mine ownerswere slow in approving this compressed gas material breaking methodbecause of the amount of special cartridge charging equipment requiredand the troublesome trame problem created by the need for moving theequipment into several locations during each working shift.

Up to the time of the development of this invention, it was consideredto be necessary to employ one of the following types of mechanisms forcharging cartridges after they were placed in drill holes formed in thecoal to be broken down:

1. A transportable charging plant, including a compressor and a receivermounted on a wheel or traveling-tread supDOfted Chassis Which h ad to bemoved into proper operating relation w1th respect to each location inwhich it was to be used in breaking down coal. The cartridge orcartridges to be charged by the plant were connected to the receiver bytubing which had to be strong enough to withstand internal pressuresranging as high as approximately 12,000 pounds per square inch and yetbe flexible enough to allow for easy manipulation. Copper tubing havingan outside diameter of of an inch and a wall thickness of s of an inchwas used for this purpose.

2. Av transportable receiver unit consisting of a single tank, or aseries of tanks, mounted 0n a wheeled chassis and charged with thecompressed gases at a stationary, central charging plant and moved intoproper operating relation with respect to each location in which it wasto be used in breaking down coal. The cartridge or cartridges used inconnection with such a unit had to be connected to the tank or tanks inthe same way as when a transportable charging plant was employed.

There were several principal objections to the use of transportablecharging plants for charging the cartridges after they were placed inthe drill holes in the material to be broken down. The first of theseobjections involved the added cost required to render such acompressor-receiver assembly light enough and compact enough to permitit to be easily moved through entries of conventional dimensions so thatthe plant could be operated in several different locations during eachworking shift. As such a transportable charging plant possessed acapacity which was only suiiicient to charge enough cartridges to breakdown from 700 to '750 tons per working shift, it was necessary for evena reasonably large mine to employ several of these plants to break downthe tonnage required for a normal days operation. Additionally, eachcharging plant in operation required a horse power electric motor tooperate the same with the result that the simultaneous use of severalcharging plants would add very materially to the power load of a mine.This power load problem was found to be very serious because very fewmines have any surplus power during a working shift. It, therefore, wasfound to be necessary for a mine to either enlarge its power developingequipment or limit its use of cartridge charging plants to oi shifts.ASuch a restriction on the use of compressed air for material breakingpurposes destroyed an important advantage this method possessed over theuse of explosives because practically all State mining laws permitmaterial to be broken down with compressed air during working shifts.

These same State laws prohibit the use of explosives during workingshifts.

A second serious objection to the use of transportable charging plantsinvolved interference with normal traflic. As it was necessary to moveeach one of these plants from one location to another several timesduring a single shift, the use of several plants added a material burdento the trackage systems which, as laid out, were only capable ofsatisfactorily handling the normal underground equipment.

A third serious objection had to do with the problem of obtaining fromeach transportable charging plant the tonnage per shift it was capableof breaking down. To be able to operate such a plant at its maximumcapacity of '700 to r750 tons per shift, the coal to be broken down mustbe fairly well concentrated. This operating condition is not a desirableone because of the corresponding concentration of other equipment on thetrackage system. The traiiic burden placed on any trackage system can bebest taken care of if operations are being carried on in several, fairlywell separated locations.

The use of transportable receiver units provides the same trafficproblems as the use of transportable charging plants. In fact, areceiver unit has to be moved more frequently than a charging plantbecause of its limited capacity. For example, if a greater number shotsare to be fired at a given location than can be charged from a receiverunit, it becomes necessary to either move two units into that locationor interrupt the material breaking operation while an emptied receiverunit is returned to the central charging plant for recharging and thenmoved back to the said location for completion of the operation.

These transportable receiver units, however, do eliminate the need foremploying more than one charging plant and this plant can be of a heavyduty type because it is not necessary to transport the same.

The daily capacity of even the most efficient type of transportablereceiver unit so far developed is only about one-half to one-third thatof a transportable charging plant. It will be appreciated therefore,that even under the most favorable operating conditions, the equipmentof a mine must 'be increased by a considerable number of units iftransportable receivers are employed for charging the compressed aircartridges.

The primary object of this invention is the provision of apparatus forcharging with compressed gas the reusable cartridges employed forbreaking down coal, or the like, in mines which, as compared with eithertransportable charging plants or receiver units, greatly reduces theamount of special equipment required for and the initial, powerconsumption, and maintenance costs of an installation; which practicallyeliminates the need for reserve or idle equipment; which increases to asubstantial extent the daily tonnage yield per dollar of initial costand the flexibility of this type of material breaking apparatus; andwhich entirely removes all obstructions to normal underground traiicwithout requiring any modification of the original or conventionaltrackage system.

Another important object of this invention is to provide a cartridgecharging system that employs a fixed, central charging plant as theoriginal source of compressed gas; that provides all mine rooms orlocations being worked with gas obtainable from a closely positionedreceiver which is of ample capacity and is constantly maintained chargedto a sufficiently high pressure to permit cartridges to be quicklycharged therefrom in relatively rapid succession without causing thereceiver pressure to drop below the desired maximum operating pressureof the cartridges; and that eliminates all need for moving heavy orbulky equipment over the trackage system of a mine.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings forming a part of this specification and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a vertical sectional view, partly broken away, of a coalmine in which has been installed one form of apparatus embodying thisinvention,

Figure 2 is a fragmentary, horizontal sectional View of a portion of themine and apparatus illustrated in Fig. 1 and discloses specifically theapproved practice of locating the cartridge shooting or control valvesin a cross-cut or a break-through between two entries, rooms, or thelike,

Figure 3 is a fragmentary horizontal sectional view, partly broken away,of a coal mine in which a slightly different apparatus arrangement,embodying this invention, has been installed,

Figure 4 is a fragmentary, horizontal sectional view of a. coal minewith a further embodiment of the invention installed therein, and

Figure 5 is a fragmentary, vertical sectional view taken on line 5-5 ofFig. 4.

In the drawings, wherein for the purpose of illustration are shown thepreferred embodiments of this invention, and first particularlyreferring to Figs. 1 and 2, there is disclosed a fragmentary portion ofa coal mine, or the like, which includes the main shaft 5 connected atits lower end to the parallel entries 6 that follow the vein of coal 1.At a distant point from the shaft 5 is located the face 8 of the coalvein which is being worked upon; i. e., is being broken down by means ofcharges of compressed gas, such as air, at a pressure which is usuallyaround 9000 or 10,000 pounds per square inch, but which may undercertain operating conditions reach as high as 12,000 pounds per squareinch. These material breaking charges are released from one or morereusable cartridges 9 which are placed in suitable drill holes formed inthe working face. These compressed air cartridges may be of theconstruction covered by my Patent No. 2,083,548, issued June 15, 1937.This prior patent discloses a cartridge structure from which acompressed air charge is released, at any desired pressure, by means ofa valve, which is actuated to effect release of the charge by means of adiierential fluid pressure operated mechanism. This mechanism isactuated by venting the compressed air from a relatively small controlchamber through the tubing employed to deliver the charge to thecartridge when positioned within a drill hole.

Fig. 1 discloses a building I0 which is located on the mine property atthe surface and adjacent the upper end of the shaft 5. This building mayeither be the engine house of the mine or any other existing orspecially built enclosure. This building l0 is intended to house astationary gas 'by appropriate couplings.

compressor, not shown, which is capable of compressing gas a suitableamount in excess of the maximum material breaking pressure to be used inthe cartridges to be charged by this compressor. It is preferred thatthe compressor be capable of building up a pressure which will exceedthe normal cartridge charging pressure by from 250 to 500 pounds persquare inch.

A main line of steel tubing II is connected to the compressor at itsupper end and extends over to and down the shaft 5. Thissteel tubing II,also, extends through the appropriate mine entries 6 to all of thesections or locations of the mine in which the coal is being brokendown. This tubing II, of course, is made up of sections of convenientlength which are interconnected No attempt has been made to illustratethis sectional construction of the tubing and the couplings with theexception of the points at which the tubing branches or changes itsdirection. This tubing, of course, is permanently attached to a side ofthe mine shaft and either a side wall or the roof of the entries bymeans of suitable pipe hangers or straps.

`This steel tubing II is intended to function as a receiver and is fullycharged with compressed air at the desired pressure. By extending thistubing type of receiver to all sections or locations of the mine wherematerial is being broken down, these various sections or locations areprovided with an adequate supply or volume of compressed air for rapidlycharging cartridges at a desired rate and without causing the receiverpressure to drop to any material extent. To permit the receiver II toaccomplish this desired result, it should have a volumetric capacity foreach section or location of the mine of at least 10,000 cubic inches.That is to say1 if the receiver II extends to and serves three differentmine sections or locations, the total volumetric capacity of thereceiver should at least equal 30,000 cubic inches. It has beendetermined that the volume of compressed air used at any one location orsection of a mine will not exceed from 200 to 300 cubic inches perminute. If the receiver I I has a volumetric capacity, for each minesection or location to be served, of approximately 11,000 cubic inches,and the inside diameter or bore of the steel receiver tubing is not lessthan 5A, of an inch in diameter, the drop in pressure at all of the minesections or locations will be nil. With the inside diameter of thereceiver being at the minimum value of of an inch, the receiver musthave a length equal to 3000 feet times the number of mine locations orsections being served. Of course. as the inside diameter of the receiveris increased from the 5/8 inch minimum, the desired volumetric capacitymay be obtained with a total length Which is less than 3000 feet foreach section or location.

In the specic illustration of Figs. 1 and 2, the receiver II extends toa point which is located a suitable distance from the face 8 of the coalvein being broken down. As the entries 6 are being extended in thisillustration, the receiver is illustrated as stopping at this section orlocation of operation. The receiver II terminates at the elbow couplingI2 which is located at one end of the cross-cut I3 which extends betweenand connects the parallel entries 6. From this elbow I2, copper tubingIl extends into the cross-cut and is connected at its outer end to thediagrammatically illustrated mechanism I5 which consists of a suitableshooting or control valve and a pressure gauge. This shooting or controlvalve may be considered as being of the type disclosed and claimed in mypreviously issued Patent No. 2,146,879, dated February 14, 1939,although numerous refinements have been incorporated in the shooting orcontrol valve mechanism now being commercially used which are notdisclosed in this last mentioned patent. Any suitable pressure gaugewhich will record or'register the high pressures-used in this type ofsystem can be em` ployed in connection with the shooting or controlvalve. From this control mechanism I5, copper tubing I5 extends to theworking face 8 and is properly attached to the cartridge 9.

This copper tubing must be strong enough to withstand the high internalpressures to which itis subjected and, additionally, it must besufliciently flexible to permit it to be properly manipulated withoutrupturing. A copper tubing which will respond to these requirementspossesses an outside diameter of of an inch `and a wall thickness of 116of an inch. It will be appreciated, therefore, that the aforementionedminimum inside diameter for the receiver II provides a cross sectionalarea which is approximately 25 times the cross sectional area providedby the inside diameter of the copper tubing I4 and I6. With the point ofconnection to the receiver located within or'150 feet of the workingface 8 of the coal vein, and with the receiver charged to a pressurewhich will exceed the desired material breaking pressure charged intothe cartridge 9 by approximately 250 pounds per square inch, it willrequire less than ten seconds to charge the cartridge. The principalreason for requiring a cartridge to be charged at as rapid a rate aspossible is the time it saves for the shot firing crew.

In the use of the apparatus, or system, disclosed in Figs. 1 and 2, thecartridge 9 is placed in a drill hole formed in the working face 8 andthe shot firing crew then retires to the cross-cut I3 so that thecontrol mechanism I5 may be manipulated. The valve of this mechanism isthen operated to cause the compressed air to ow from the receiver II tothe cartridge 9 through the copper tubing I 4 and I6. When the pressuregauge of the mechanism I5 registers the desired pressure, the valve ofthe control mechanism is again actuated to shut oi the ilow ofcompressed air from the receiver I I and to vent the air from thecontrol chamber of the cartridge 9 and the copper tubing I6. Thisventing results in manipulation of the valve operating mechanism of thecartridge to cause the valve to be opened to release the compressed aircharge into the drill hole to break down the coal. The cartridge 9 isthen recovered from the broken down coal and is inserted in the nextdrill hole to be red.

The location of the compressor at the surface like in Fig. 1, or atleast close to the foot of the shaft 5, is very desirable because itmakes the use of an A. C. electric motor for driving the compressoreconomically practical. Alternating current motors are more satisfactoryfor this type of service because they provide a more dependable, steadysource of power and are less expensive to operate. Mines usually areWired for direct current because of the variable speed motors requiredfor driving the mine locomotives, etc. Therefore, any need foralternating current at a point in a mine which is remote from the sourceof electricity makes it necessary to wire the mine for both types ofcurrent. Running the receiver II from the surface to the remotelocations is not the equivalent of wiring for alternator more additionalsections or locations of the mine where, it is to be presumed,additional material breaking operations are being performed.

This installation is operated on the principle of having the compressorI8 located in one of the cross-cuts I9 which extends between theparallel entries 6. The location of the compressor in this cross-cutremoves the same from the entries and the several rooms so that thecompressor will not interfere in any way with traffic on theconventional trackage system, not shown. Although this compressor I8 isillustrated as being positioned in a cross-cut, it is to be understoodthat the compressor might just as well be located in the undergroundrepair shop, which is generally located fairly close to the foot of themain shaft, and in which coal loaders, locomotives, and the like areserviced.

The receiver II, which corresponds in every respect with the receiver ofFigs. 1 and 2, extends from the compressor I8 along one of the entries 6to all of the various sections or locations in which material breakingoperations are being performed. This receiver, therefore, extends pastthe location or section of the mine which includes the rooms Il. Tcouplings 20 are connected in the receiver II to permit the coppertubing 2I to be connected to the receiver for supplying the rooms I1with compressed air for breaking down the coal. These two lengths oftubing 2| extend to the respective cartridge shooting or control valvesand gauges which are again designated by the reference character I5.From these control mechanisms I5, copper tubing 22 extends to the fourcartridges 9. Each one of these cartridges is being employed in a roomI'I to break down the coal from a working face 8. As shown, thesecartridges are being fired in pairs; i. e., two cartridges aresimultaneously controlled by a single mechanism I5. The tubing 2I and 22is the same as the tubing I4 and I6 of Figs. l and 2. The controlmechanisms I5 in this layout are located in the break-throughs 23,instead of being located in a cross-cut like the illustration of Figs. 1and 2. In all such operations, the control mechanism mustbe located atsome point which is around at least one corner from the working facebeing broken down. To comply with the various State mining laws, themembers of the shot firing crews are required to be out of alignmentwith the cartridges being operated so that they will not be injured incase a cartridge fiies out of its drill hole when its compressed aircharge is released.

Figs. 4 and 5 may be considered as illustrating a layout in which anentirely new part of the mine is being opened up. That is to say, theprevious operations have been served by the entries 6 which extend fromthe shaft, not shown, to the various sections or locations which havebeen worked out. This portion of the mine has been closed oil. and thereceiver I I that served the same has been removed. The new entries 6ahave been formed in this new portion of the mine to a suiiicient extentto accommodate the various rooms 24. As operations in this new portionof the mine will be carried on for a tridges 9 attached to their outerends.

considerable iengtn of time. tne underground compressor unit I8 has beeninstalled in one of the cross-cuts, 25. This location for the compressoris relatively close to the rooms 24. For that reason, a receiver ofproper volumetric capacity to serve the rooms 2l will not be provided bymerely running the receiver out to one of the entries 6a and then oncealong the length of this entry. To provide the proper capacity, thereceiver II is doubled back and forth several times in the short lengthof the entry 6a. Suitable return bends 26 may be employed forinterconnecting the adjacent ends of the several lengths of steel tubingwhich forms this type of receiver assembly. It will be appreciated thatas the entries 6a are extended farther into this newly opened portion ofthe mine, the receiver lII may be straightened out so that it finallywill extend along the entry in the manner illustrated in Figs. l to 3inclusive. However, the compressor I8 may remain in this initiallocation during the entire time this portion of the mine is beingworked.

From suitable T couplings 2l, connected in the outer length of thereceiver, copper tubing 28 extends into the rooms 24 for serving thecontrol mechanisms I5. These control devices are connected to coppertubes 29 which have the car- These cartridges are being employed forbreaking down coal from the working faces 8.

From the above descriptions of the installations in three diiferent minearrangements, it will be appreciated that the material breakingapparatus embodying this invention can be installed so as to take careof any situation which might be encountered in different mines.Therefore, the invention should in no way be limited to the specificarrangements illustrated by the several figures.

It will be noted that the compressors are shown as being positionedeither on the surface, entirely outside of a mine, or at any suitablelocation within a mine which will not obstruct normal undergroundtransportation. As the compressors are seldom moved, they can be madelarge enough to possess the desired capacity and to be a dependablemachine. The cost, per rated horsepower, will be less for this type of astationary unit than for a charging plant which is designed so that itmay be moved from place to place through the mine entries. 'I'helocation of the compressor outside of the mine has the eiect ofmaterially lengthening its working life because it is not subjected tothe dust laden air of the mine. When the compressor is located in theengine house, on the surface, it may be kept under constant supervisionby the mine engineers. Also, it can be worked on when the mine is idle.This is not the case with a compressor located at some out of the wayspot in the mine.

By forming the receiver II of interconnected lengths of steel tubing,the receiver can be extended into all portions of a mine so that everylocation or section being worked is provided with adequate receiverservice. As one section or location of a mine is lcompletely worked outand abandoned, the portion of the receiver that served that section orlocation can be dismantled without interrupting operations in any otherportion of the mine and the sections of tubing which constituted thedismantled portion of the receiver can be used again in extending thereceiver into newly opened sections or locations.

With this type of installation, there is no rolllng stock which must bemaintained, like with the two types of transportable cartridge chargingmethods described above, and the compressor constitutes the only pieceof equipment which possesses movable parts that are subject to wear. Thesections of steel tubing employed to form the receiver are subject topractically no wear and tear and will last indefinitely. It has beendetermined that this type of receiver system may be extended throughseveral miles of mine entries and all sections or locations of the minewill be properly served with compressed air at the desired pressure andvolume. This is due to the fact that uniform pressure is maintained inthe receiver right up to the extreme outer end of the same.

It was noted above that the capacity of a transportable charging plantwas limited to a considerable extent by, or was dependent upon, theextent to which the coal being broken down was concentrated. It,additionally, was pointed out that mine operators prefer to have thesections or locations of the mine being worked fairly well separated orscattered so that traiiic jams would not occur. With this type ofcharging apparatus, it makes no difference whether the locations orsections being worked are concentrated or widely scattered. The capacityof the system is the same in either case.

It was further explained above that when transportable charging plantsor receiver units are used, it usually is necessary to have reserveplants or units which are idle at least a part of each shift. No suchidle equipmentis needed for the type of system embodying this invention.

As only one compressor need be employed with the present system, therewill be a considerable saving in horse-power consumption as compared toa system employing transportable compressor plants which must beprovided in proper number to supply all sections or locations of a minebeing worked.

Fig. 1 discloses the receiver Il as extending from the surface into themine through the main shaft of the mine. It is to be understood,however, that a special, small diametered hole may be drilled from thesurface to the mine level at any other point on the mine property andthe receiver may be placed in this special hole. A compressor then maybe located on the surface adjacent the upper end of the receiver holeand enclosed in a suitable building or housing provided especially forthat purpose. Such an arrangement may be found to be desirable for alarge mine where all of the operations are being carried on severalmiles from the main shaft. In such a situation, it would be impracticalto have the receiver extend from the surface down the main shaft andalong these several miles of entries to the active portion of the mine.All of this long stretch of receiver equipment is not needed to providethe required receiver capacity. Of course, the same situation can betaken care of by a compressor located in the mine. Some mine operators,however, strongly favor locating the compressors on the surface.

It is to be understood that the forms of this invention herewith shownand described are to be taken as preferred examples of the same, andthat various changes in the shape, size, and arrangement of parts may beresorted to without departing from the spirit of the invention or thescope of the subjoined claims.

through the entries, or the like, to a mine section in which coal isbeing broken down, said relceiver having a volumetric capacity and beingcharged with gas at a pressure which will permit cartridge charges to bequickly withdrawn therefrom in relatively rapid succession withoutcausing the receiver pressure to drop below the desired maximumoperating pressure of a cartridge, a discharge line extending from theworking face of the coal to the receiver and connected to the latter, acartridge, having differential gas pressure operated dischargemechanism, connected to the discharge line, and means in said dischargeline for controlling ow of gas to the cartridge and for controllingoperation of the discharge mechanism of the cartridge to eiect releaseof a material breaking charge.

2. A material breaking system for coal mines, or the like, comprising acompressor stationed on the mine property, a compressed gas receiverconnected to the compressor and extending through entries, or the like,in the desired directions to the several sections f a mine in which coalis being broken down, said receiver having a volumetric capacity foreach of said mine sections and being charged with gas at a pressurewhich will permit cartridge charges to be quickly withdrawn therefrom atany desired number of said sections in relatively rapid successionwithout causing the receiver pressure to drop below the desired maximumoperating pressure of any of the cartridges being employed at theseveral sections, a discharge line extending from the working face, ofthe coal at each section to an adjacent portion of the receiver andconnected to the latter, a cartridge having differential gas pressureoperated discharge mechanism connected to each of the discharge lines,and means in each discharge line for controlling ow of gas to itscartridge and for controlling operation of the discharge mechanism ofits cartridge to elect release of a material breaking charge.

3. A material breaking system for coal mines, or the like, comprising acompressor stationed on the mine property, a compressed gas receiverconnected to the compressor and extending through entries, or the like,to a mine section in which coal is1 being broken down, said receiverhaving a volumetric capacity of at least 10,000 cubic inches and beingcharged with gas at a pressure suiilciently in excess of the requiredmaterial breaking pressure to permit cartrige charges to be quicklywithdrawn therefrom in relatively rapid succession without causing thereceiver pressure to drop below the said required material breakingpressure, a discharge line extending from the working face of the coalto the receiver and connected to the latter, a cartridge, havingdifferential gas pressure operated discharge mechanism, connected to thedischarge line, and means in said discharge line for controlling flow ofgas to the cartridge and for controlling operation of the dischargemechanism of the cartridge to eilect release of the material breakingcharge.

4. A material breaking system for coal mines, or the like, comprising acompressor stationed on the mine property, a compressed gas receiverconnectedV to the compressor and extending through entries, or the like,in the desired directions to the several sections of the mine in whichcoal is being broken down, said receiver having a volumetric capacityfor each of said mine sections of at least 10,000 cubic inches and beingcharged with gas at a pressure which will be sufiiciently in excess ofthe required material breaking pressure to permit cartridge charges to-be quickly withdrawn therefrom at any desired number of said sectionsin relatively rapid succession without causing the receiver pressure todrop below the said required material breaking pressure, a dischargeline extending from the working face of the coal at each section to anadjacent portion of the receiver and connected to the latter, acartridge, having differential gas pressure operated dischargemechanism, connected to each one of the discharge lines, and means ineach discharge line for controlling flow of gas to its cartridge and forcontrolling operation of the discharge mechanism of its cartridge toeffect release of a material breaking charge.

5. In a material breaking system for coal mines, or the like, acompressor stationed in a building on the surface of the mine, acompressed gas receiver connected to the compressor and extending downthe mine shaft and through entries, or the like, to a mine section inwhich coal is being broken down, said receiver having a volumetriccapacity and being charged with gas at a pressure which will permitcartridge charges to be quickly withdrawn therefrom in relatively rapidsuccession without causing the receiver pressure to drop below thedesired maximum operating pressure of a cartridge, a discharge lineextending from the working face of the coal to the receiver andconnected to the latter, a cartridge, having differential gas pressureoperated discharged mechanism, connected to the discharge line, andmeans in said discharge line for controlling iiow of gas to thecartridge and for controlling operation of the discharge mechanism ofthe cartridge to effect release of a material breaking charge.

6. A material breaking system for coal mines, or the like, comprising acompressor stationed in a building on the surface of the mine. acompressed gas receiver connected to the compressor and extending downthe mine shaft and through entries, or the like, in the desireddirections to the several sections of the mine in which coal is beingbroken down, said receiver having a volumetric capacity for each oi'said mine sections and being charged with gas at a pressure which willpermit cartridge charges to be quickly withdrawn therefrom at anydesired number of said stations in relatively rapid succession withoutcausing the receiver pressure to drop below the desired maximumoperating pressure of a cartridge, a discharge line extending from theworking face of the coal at each section to an adjacent portion ofthereceiver and connected to the latter, a cartridge, having differentialgas pressure operated discharge mechanism, connected to each dischargeline, and means in each discharge line for controlling flow of gas toits cartridge and for controlling operation of the discharge mechanismof the cartridge to effect release of a material breaking charge.

'7. A material breaking system for coal mines, or the like, comprising acompressor stationed in the mine at a point where it will offer noobstruction to normal underground trailic, a compressed gas receiverconnected to the compressor and extending through entries, or the like,to a mine section in which coal is being broken down, said receiverhaving a volumetric 75 capacity and being charged with gas at a pressurewhich will permit cartridge charges to be quickly withdrawn therefrom inrelatively rapid succession without causing the receiver pressure todrop below the desired maximum operating pressure of a cartridge, adischarge line extending from the working face of the coal to thereceiver and connected to the latter, a cartridge, having diierentialgas pressure operated discharge mechanism, connected to the dischargeline, and means in said discharge line for controlling fiow of gas tothe cartridge and for controlling operation of the discharge mechanismof the cartridge to eiect release of a material breaking charge.

8. A material breaking system for coal mines, or the like, comprising acompressor stationed in the mine at a point where it will oiTer noobstruction to normal underground traic, a compressed gas receiverconnected to the compressor and extending through entries, or the like,in the desired directions to the several sections of the mine in whichcoal is being broken down, said receiver having a volumetric capacityfor each of said mine sections and being charged with gas at a pressurewhich will permit cartridge charges to be quickly withdrawn therefrom atany desired number of said sections in relatively rapid successionwithout causing the receiver pressure to drop below the desired maximumoperating pressure of a cartridge, a discharge line extending from theworking face of the coal at each section to an adjacent portion of the-receiver and connected to the latter, a cartridge, having differentialgas pressure operated discharge mechanism, connected to each dischargeline, and means in each discharge line for controlling flow of gas toits cartridge and for controlling operation of the discharge mechanismof its cartridge to effect release of a material breaking charge.

9. A material breaking system for coal mines, or the like, comprising acompressor stationed on the mine property, a compressed gas receiverformed of connected sections of tubing having an inside diameter 0f atleast 5A; of an inch and a total length which will provide a volumetriccapacity of not less than 10,000 cubic inches connected to thecompressor and extending through entries, or the like, to a mine sectionin which coal is being broken down, said receiver being charged at apressure sufficiently in excess of the required material breakingpressure to permit cartridge charges to be quickly withdrawn therefromin relatively rapid succession without causing the receiver pressure todrop below the desired maximum operating pressure of a cartridge, adischarge line extending from the working face of the coal to thereceiver and connected to the latter, a cartridge, having differentialgas pressure operated discharge mechansm, connected to the dischargeline, and means in said discharge line for controlling flow oi' gas tothe cartridge and for controlling operation of the discharge mechanismof the cartridge to effect release of a material breaking charge.

l0. A material breaking system for coal mines, or the like, comprising acompressor stationed on the mine property, a compressed gas receiverformed of connected sections of tubing having an inside diameter of atleast of an inch and a total length which will provide a volumetriccapacity of not less than 10,000 cubic inches for each section orlocation of the mine being worked, said receiver being connected to thecompressor and extending through entries, or the like, in the desireddirections to the several sec'v tions of the mine in which coal is beingbroken down and being charged at a pressure sufliciently in excess ofthe required material breaking pressure to permit cartridge charges tobe quickly withdrawn therefrom at any desired number of said sections inrelatively rapid successionwithout causing the receiver pressure to.drop below the desired maximum operating pressure of a cartridge, adischarge line extending from the working face of the coal at eachsection to an adjacent portion of the receiver and connected to thelatter, a cartridge, having differential gas pressure operated dischargemechanism, connected to each discharge line, and means in each of saiddischarge lines for controlling flow of gas to its cartridge and forcontrolling operation of the discharge mechanism' of the cartridge toeffect release of a material breaking charge.

11. A material breaking system for coal mines, or the like, comprising acompressor stationed on the mine property, a. compressed gas receiverconnected to the compressor at one end and formed o! connected sectionsof tubing doubled back and forth along an entry from the compressor to amine section in which coal is being broken down, said receiver having avolumetric capacity and being charged with gas at a pressure which willpermit cartridge charges to be quickly withdrawn therefrom in relativelyrapid succession without causing the receiver pressure to drop below thedesired maximum operating pressure of a cartridge, a discharge lineextending from the working face of the coal to the receiver andconnected to the latter, a cartridge, having differential gas pressureoperated discharge mechanism, connected to the discharge line, and meansin said discharge line for controlling flow of gas to the cartridge andfor controlling operation of the discharge mechanism of the cartridge toeiect release of a material breaking charge.

vFRANK H. ARMSTRONG.

